Consider making --headless be the default for Edge

[dandclark]

#44515 made --headless the default for Chrome and Chromium. Should Edge also make this change?

cc @captainbrosset

[gsnedders]

There's some potential risk here (differences between headless and non-headless); from memory for Chrome we explicitly pass --no-headless on the bots, so any change here should do likewise.

But in general if y'all working on Edge think this is fine, I think you should file a PR to do this?